tailhook
A tailhook, also arresting hook or arrestor hook, is a device attached to the empennage (rear) of an aircraft. It is used to achieve rapid deceleration after landing, usually aboard an aircraft carrier.
Description
The tailhook is a strong metal bar, with its free end flattened out, thickened somewhat, and fashioned into a claw-like hook. The pilot is capable of raising this bar to its inflight position or lowering it ("Hook Down") for landing. Helicopters and other aircraft that are able to land vertically are not equipped with tailhooks.
Aircraft land on the flight deck of an aircraft carrier on a short "landing area", towards the aft end of the ship. A number (usually four) of very greasy and very strong thick flexible cables called arrestor cables, "arresting wires" or "cross deck pendandts" are stretched across the landing area. When an aircraft lands properly, the tailhook should catch one of the cables and the cable will transfer the energy of the aircraft, through a "purchase cable," to the belowdecks arresting gear engines, stopping the aircraft. Both the hook and cables have to be very strong: aircraft land on carriers at full throttle, so as to have enough power to go around if the hook misses all the cables.
The term "hooked" is sometimes used to describe aircraft fitted with a tailhook. An aircraft which misses a landing by failing to catch the arresting cables is said to have "boltered." Occasionally, the tailhook bounces over one or more of the wires, resulting in a "hook skip bolter."
Land-based tailhooks
Most land-based fighters also have tailhooks. In case of a brake malfunction, an aborted takeoff, a tire explosion, or a related problem, a tailhook can stop the aircraft in a departure-end or approach-end cable arrestment. Since it is an emergency equipment, the tailhook is deployed with nitrogen pressure instead of using the aircraft's hydraulic system. Additionally the tailhook can only be repositioned by ground crew.
The presence of a tailhook is not evidence of an aircraft's carrier-operations ability as land-based aircraft landing gear and tailhooks are not strong enough to absorb the impact of a carrier landing.
Gallery
Image:Tail_hook_catched.jpg|A successfully landed F/A-18. Note the engines are at full throttle.
Image:Tail_hook_missed.jpg|A missed landing (bolter).
Image:Tail_hook_detail.jpg|Detail of a tailhook.
Image:Fa18_hook.jpg|F/A-18E Super Hornet with hook, from below.
Image:TailhookCVA59G008.jpg|Tailhook down on an A4D approaching its ship for recovery
Image:F-15 Tail Hook.jpg|An airman works on the resting hook of a USAF F-15 Eagle aircraft.
Image:USAF F-16 hooks an arresting cable.jpg|A USAF F-16 hooks an arresting cable during a test at Shaw Air Force Base.
References
 United States Air Force.  . Guide To Mobile Aircraft Arresting System Installation. Retrieved on 3 November, 2007.
External links
Aircraft carriers of the USA Navy
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